Arthur c



Oct. 1, 1929. c GAYNQR 1,729,740

ATTACHMENT PLUG CAP Filed Nov. 4, 1924 ARTHUR C. GAY/VOR- Patented (let.1, 1929 @FFEQE ARTHUR G. GAYNOR, OF STRATFOED, CDNNECTICUTATTACHMENT-?LUG CA]? Application filed November 4, 1824.

My present invention relates to an attachment plug cap of the type usedto tap an electric circuit through a pair of contact blades adapted tobe inserted into suitable sockets in the circuit.

Attachment plug caps ofthis type have heretofore been constructed ofblocks of insulating material, usually of porcelain, or of compositionsof phenol-formaldehyde derivatives, pitch and asbestos, shellac or othersimilar materials, in which suitable anchorages for the contactterminals have been cast. As these materials are usually brittle and notcapable of withstanding blows or rough usage, the caps must be madelarge and heavy in order to provide the requisite mechanical andelectrical strength. Moreover, during the casting of the caps, they areliable to warp and thus throw the mounting of the terminal elements outof their proper relative positions making it diflicult to mount orinsert the cap in its socket when being connected for use.

As it is not safe to depend on the attachment of the wires to thecontact terminals for securing the wires in the plug cap, these wireshave heretofore been anchored in the cap by forming a holding knot inthe wires between their attachment to the contact terminals and anoutlet opening for the'wires so that, when a pull is exerted on thewires, the knot is brought against the inner face of the cap surroundingthe opening and the stress imparted through the wires is thus receivedon the cap rather than being imposed directly on the contact terminals;The formation of such anchoring knots, however, uses up considerablewire, which, in cases 40 where a large number of caps are attached towires, forms a considerable item of expense.

An object of my present invention is to provide a light, strong, compactand rigid attachment plug cap.

Another object of the invention is to provide an attachment plug capwhich avoids the necessity of using cast insulating supports for thecontact terminals and to support the terminals in plates or other formsSerial No. 747,733.

of insulation in which they may be easily and accurately inserted andmounted.

A further object of the invention is to provide an attachment plug capin which the terminal wires may be secured or anchored without thenecessity of forming an anchoring knot and consequently with aconsiderable saving of wire.

A still further object of the invention is to provide a contact terminalblade of a single, unitary structure, which may be stamped from a singlesheet or strip of metal.

Another object of the invention is to pro vide a method of makingcontact blades or other similar devices in a stamping opera tion from asingle strip of metal.

Further objects and features of the invention are to provide an improvedmethod and means for anchoring lead wires in a holding housing, toprovide a method of forming threaded sockets for binding screws andsimilar devices by a stamping operation. and to provide a cap of thetype indicated above in which the insulating elements are protected frombreakage.

With these and other objects in view, which will appear from thefollowing description, the invention comprises, the

methods and devices described and set forth q in the followingspecification and claims.

The various features of the invention are illustrated in theaccompanying drawings, in which:

Fig. 1 is a longitudinal sectional view of an attachment plug capembodying a pre ferred form of the invention,

Fig. 2 is a plan view of the cap shown in Fig. 1 with the metal housingremoved to show the arrangement of the lead wires on the insulatingelements and contact terminals.

Fig. 3 is a perspective view of the various elements of the plug partlydisassembled to show the construction of the cap and the connection ofthe wires therein.

Fig. 4: is a plan view of a supporting insulating plate forming a partof the attachment plug cap.

Fig. 4 is a bottom plan View of a shell enclosing the insulating plate.

v fied form of the invention,

Fig. 8 is a plan view of the cap of Fig. 7 with an outer metallic shellor casing re moved to reveal the insulating elements and their relationto the lead wires and contact terminals,

Fig. 9 is a perspective view of. a modified form of terminal, and,

Fig. 10 is a detail sectional view showing the manner of mounting thisterminal in a plate of insulating material.

In my present invention, the contact blades are mounted on an insulatingplate, which is enclosed on all sides, except that from which the bladesproject, by a protecting shell or housing of suitable material, such asspun metal. The supporting, insulating plate may be of any suitablecomposition stamped to the requisite size and shape and in which arealso stamped suitably spaced holes into which the blades are driven andtightly held in their proper spaced positions. The blades project fromthe exposed face of the supporting plate and also extend in the oppositedirection through the. plate to its opposite, covered face, and arethere connected to the ends of the lead wires, which enter the closingshell through an entrance opening. The lead wires are separated be tweenthis opening and their attachment to the blade terminals and a separatorof insulating material is placed between the sep arated wires and givena quarter turn, thus imparting a bend to the wires. A Washer ofinsulating material is then placed on the separator and, when theenclosing shell is mounted in position, the washer and separator arepressed tightly onto the supporting plate, holding the lead wires intheir bent positions and preventing them from being pulled through theentering opening and from transmitting a pull to the blade terminals.

Referring to the accompanying drawings, and more particularly to Figs. 1to 6 inclusive, a pair of contact blade terminals 11 and 12 are mountedin spaced relation on a plate 13 of insulating material such as treatedor untreated paper and project from one face 14 of the plate for asufficient distance to enter the openings of a receiving socket. Theplate 13 is made of a sheet of insulating material in which are puncheda pair of spaced openings 15 and 16 of a shape to fit that of the bladeterminals and of a size to enable the blades to be driven .thereinto andto be tightly held therein. As the holes are punched in a plate ofseasoned material their position may be accurately fixed by the punchthus insuring an accurate positioning of the contact blades.

The plate 13 is enclosed, with the exception -of the face 1 1 by aprotecting shell 17 havpassage therethrough of inwardly bent lips 21 and22, respectively, on the edge portion 18 of the shell 17, and theportions 23 and 24 of the circumference of the plate between thesenotches is slightly rounded at the face 14 to permit the lips to begiven a quarter turn and engage the edge of the plate. From the edgeportion 18 the shell extends from the plate 13 to form an enclosingportion 25 and is continued to a top portion 26 having a central opening27 through which enters a cord 28 having a pair of lead wires 29 and 30.

Within the shell 17 the lead wires 29 and 30 are separated and one wire29 is attached to the terminal blade 11 by means of a binding screw 31threaded in a socket 32 in the inner end of the blade and the wire 30 issimilarly attached to the blade 30 by means of binding screw 33 threadedin a socket 34 in the end of the blade 30. A separator plate 35,preferably of circular shape, is then inserted between the separatedportions of the wires 29 and 30, the wires being then received indiametrical notches 36 and 37 respectively. A short length of wire isleft between the separator plate and the terminals of the blades 11 and12 and by. rotating the plate 35 on its center, as indicated by thebroken arrow in Fig. 2, and pressing it towards the supporting plate 13,these lengths of wire are pressed tightly against the inner face 39 ofthe plate lie 13 and are bent at a sharp angle as they enter the notches36 and 37 The sharp bends in the wires at this point transmit anypulling forces to the separator plate 35 and prevent the loosening ofthe wires without the lifting and rotating of the plate 35 and thusserve to anchor the wires to the body of the cap.

The wires are further anchored to the cap structure by means of a washerlO-having a small diameter opening 41 through which the cord 28 extendsand the edge of which opening is sufficiently close to the innerportions of the notches 36 and 37 to tightly grip the Wires 29 and30therebetween and provide a further anchorage for the wires. The washer40 and plate 35 are pressed tightly, against each other and against theplate 13 by the top portion 26 of the shell which is shaped to fit thewasher 40.

Any suitable type of contact blade terminal may be employed, but theform of terminal shown in Figs. 5 and 6 is preferred. This bladeterminal is formed of a single strip of metal 42 havingsemi-cylindrical, threaded depressions 43 and 44 stamped in its oppositeends, the axial centers of the depressions preferably being inalignment. The strip of metal is then bent double on a line 45 midwaybetween the depressions 43 and 44 bringing faces 46 and 47 on oppositesides of the line 45 against each other and bringing the edges of thedepressions 43 and 44 into coincidence with each other. The depressions43 and 44 are so stamped that, when their edges are thus brought intocoincidence, a threaded, cylindrical screw socket 32 or 34 is formed,capable of receiving the stem of the screw 31 or 33. In the stamping ofthe blank, flanges are formed at opposite edges of the depressions 43and 44, which, when the blank is doubled, form wings preventing theturning of the blade in the opening 15 or 16. The plate 42 is alsopreferably notched as at 49 and 50 at the ends of the bending line 45 toprovide a beveled edge or corner for the blades to permit them to beeasily inserted into their sockets.

In the modification of the invention shown in Figs. 7 to 10 a differentform of contact blades and of separator plate is used than in the formof the invention described above. In the form of embodiment shown in 7to 10, a mounting insulating plate 13 and a housing or enclosing shell17 are used of substantially the same character as in the form ofembodiment shown in Figs. 1 to 6, but the openings 15 and 16 are of ashape to conform to the cross sectional form of terminals 50 and 51 usedin this form of embodiment. The terminals 50 and 51 are stamped of asingle piece of metal bent at 52 to form a pair of contiguous orabutting plate portions 53 and 54 which extend through the plate 13 andpro ject from the outer face 14 and at their other ends also extend ashort distance past the inner face 39 of the plate. The end portion 55of one of the plate portions 53 is bent sidewise to lie against the face39 and the end portion 56 of the other plate portion 54 is bent sidewisein the opposite direction to also he against the surface 39 and is thencurved upwardly at 57 and reversely to provide a portion 58 at a slightdistance above the portions 55 and 56. The end 59 of the portion 55 maythen be bent to overlie the end of the portion 58 and press against itwith a resilient pressure. In securing a wire to blade terminals of thistype the end of the wire may be inserted beneath the portion 58 and thisportion and the portion 59 then presses or is pressed or clamped down totightly hold the wire. Or in some cases, the terminal may be finishedspaced from the surface 39 so that the end of a lead wire may beinserted beneath it and held as the portion 54 is pressed downwardlyonto the surface 39 of the plate 13.

A modified form of separator disc is employed in the form of embodimentshown in Figs. 7 to 10. This separator disc comprises a disc 60 having apair of spaced openings 61 and 62 through which the lead wires 29 and 30are threaded and which upon turn ing through a quarter turn, bend thewires 29 and 30 sharply in a manner similar to that shown in Figs. 1 to6 and serves to hold or anchor the wires in the cap. The cap is alsoprovided with a washer 62 similar in form to that of the embodimentshown in Figs. 1 to 6 and resting against the top portion 26 of theenclosing shell. The disc 60 however, is preferably extended outwardlyfor a sufficient distance to be engaged by a shoulder 64 of the shell 17and pressed by this shoulder against the supporting plate 13 when theshell 17 is mounted on the plate.

The above described invention therefore provides an attachment plug capwhich is of a light weight, inasmuch as the insulating materialcomprises only a few light plates, which are, however, protected againstinjury by the enclosing metal shell. As the openings in which theterminal blades are mount ed may be accurately stamped in the materialthe blades are automatically and accurately positioned in the cap andall danger of their being displaced by a warping of the material isavoided. The anchoring of the wires in the cap by the use of theseparator disc and washer construction, which may be applied to' avariety of apparatus, enables a very strong anchorage to be effectedwith a minimum consumption of wire length.

As changes of construction could be made within the scope of myinvention, it is intended that all the matter contained in the abovedescription or shown in the accompanying drawings, shall be interpretedas illustrative and not in a limiting sense.

Having described my invention, what I claim and desire to secure byLetters Patent is:

1. A terminal blade of the type described in which comprises a strip ofmetal having a pair of complementary threaded depressions, and aradially extended wing at each end thereof and said strip being foldedmidway of said depressions to bring the edges of said depressions intocoincidence and form a screw socket.

2. A. terminal of the type described which comprises a strip of metalhaving a pair of complementary threaded depressions and radiallyextending wings at opposite ends thereof, the axes of said depressionsand the sides of the wings being respectively in alignment, said stripbeing folded double on a line midway of said depressions and wings,

ARTHUR C. GAYNOR.

